INFERIOR MESENTERIC ARTERIOVENOUS MALFORMATION AS A DIFFERENTIAL DIAGNOSIS OF INFLAMMATORY BOWEL DISEASE: A CASE REPORT

Case Presentation A 32-year-old woman has been under follow-up at the coloproctology outpatient clinic for 8 years due to increased frequency of bowel movements and the presence of blood and pus in the stool. She was previously diagnosed with ulcerative colitis based on colonoscopies showing mucosal fragility in the rectosigmoid and increased vascularization, with histopathology indicating mild congestion of the lamina propria. She was initially treated with mesalazine, and later, azathioprine, infliximab, and adalimumab were added, but the symptoms remained uncontrolled, requiring up to 7 units of packed red blood cells per month. In the most recent endoscopic exam, the sigmoid and rectal mucosa showed increased vascular patterns, with multiple angiodysplasias. This led to the exclusion of an inflammatory disease and the initiation of vascular investigation. Magnetic resonance angiography revealed the presence of multiple fine tortuous venous structures in the mesorectum and mesosigmoid, with low flow, characterizing a vascular malformation. These malformations were associated with marked diffuse circumferential thickening of the rectum and sigmoid, especially involving the submucosal layer. Both the angiography and arteriography failed to identify a predominant feeding artery or draining vein. Given the presence of malformations extending to the anal canal, the decision was made to perform an abdominoperineal amputation, with resection of the colon at the descending level and terminal colostomy. During surgery, the sigmoid appeared violet-colored, with vascular malformations visible. Histopathology confirmed an arteriovenous malformation (AVM) affecting the pericolonic adipose tissue and intestinal wall. The patient had a good recovery in both the immediate and late postoperative periods, with no further episodes of bleeding.

Discussion This case presents a diagnosis of an arteriovenous malformation (AVM) originating from branches of the inferior mesenteric artery, a less frequent location for this uncommon vascular phenomenon. AVMs are high-flow vascular malformations that cause symptoms due to reduced tissue oxygenation. In the colon, hypoxia may lead to ischemic colitis, which is often a challenging diagnosis and can mimic inflammatory bowel disease or diverticulitis. Therefore, imaging exams become a crucial tool in the diagnostic investigation.

Conclusion This case aims to highlight a rare differential diagnosis that should be considered when a patient is refractory to treatment for the primary diagnosis.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
25 April 2025